Add HID handshake_callback

It is called when the equivalent pkt is received from the HID
client as a normal response to set_report() and set_protocol_mode(),
and for errors for get_report() and get_protocol_mode().

Change-Id: I26ec37348e597f294f83907bbd256c88db5ac2ef
Signed-off-by: Mike J. Chen <mjchen@google.com>